2017A&A...604A.107R

We consider the parallaxes of sixteen cataclysmic variables and related objects that are included in the TGAS catalogue, which is part of the Gaia first data release, and compared these with previous parallax measurements. The parallax of the dwarf nova SS Cyg is consistent with the parallax determination made using the VLBI, but with only one of the analyses of the HST Fine Guidance Sensor (FGS) observations of this system. In contrast, the Gaia parallaxes of V603 Aql and RR Pic are broadly consistent, but less precise than the HST/FGS measurements. The Gaia parallaxes of IX Vel, V3885 Sgr, and AE Aqr are consistent with, but much more accurate than the HIPPARCOS measurements. We took the derived Gaia distances and find that absolute magnitudes of outbursting systems show a weak correlation with orbital period. For systems with measured X-ray fluxes we find that the X-ray luminosity is a clear indicator of whether the accretion disc is in the hot and ionised or cool and neutral state. We also find evidence for the X-ray emission of both low and high state discs correlating with orbital period, and hence the long-term average accretion rate. The inferred mass accretion rates for the nova-like variables and dwarf novae are compared with the critical mass accretion rate predicted by the Disc Instability Model. While we found agreement to be good for most systems there appears to be some uncertainty in the system parameters of SS Cyg. Our results illustrate how future Gaia data releases will be an extremely valuable resource in mapping the evolution of cataclysmic variables.